Detecting apparatus including resilient moisture absorbent roller means for locatingdiscontinuities in non-conductive coatings on conductive objects



Sept. 19, 1967 L. F. LANE A v3,343,081

DETECTING APPARATUS INCLUDING RESILIENT MOISTURE ABSORBENT ROLLER MEANS FOR LOCATING DISCONTINUITIES IN NON-CONDUCTIVE COATINGS on CONDUCTIVE OBJECTS Filed Dec. 13, 1965 INVENTOR. Lee E Lane United States Patent Office 3,343,081 Patented Sept. 19, 1967 DETECTING APPARATUS INCLUDING RESILIENT MOISTURE ABSORBENT ROLLER MEANS FOR LOCATING DISCONTINUITIES IN NON-CON- DUCTIVE COATINGS N CONDUCTIVE 0B- JECTS Lee F. Lane, Langhorne, Pa., assignor to H. C. Price Co.,

Bartlesville, Okla, a corporation of California Filed Dec. 13, 1965, Ser. No. 513,492 Claims. (Cl. 32454) ABSTRACT OF THE DISCLOSURE The electrically non-conductive coating on the outside of a length of steel pipe or the like is tested for holidays in the coating by passing the same through a discontinuity detector including an octagonal frame mounting eight rollers in an annular series of rollers comprising a pair of axially spaced, staggered banks of rollers. The rollers are constructed of sponge-like material and, therefore, are resilient as well as moisture absorbent. Each roller has a peripheral, coating containing surface which is transversely arcuate for complementally mated engagement with the coating.

The rollers are moistened with an electrically conductive fluid such as tap Water or the like and the coating is mositened prior to movement of the pipe between the rollers so that a liquid bridge is maintained between the rollers and the coating. In this respect, by virute of the staggered disposition of the rollers of the respective banks, the bridge encompasses the entire circumference and traverses the entire length of the coating.

A solenoid actuated marking device is coupled with the source of electricity by a normally interrupted circuit, one end of which is connected to the rollers and the other end of which is connected to the pipe. Thus, Whenever a discontinuity in the coating is traversed by the fluid bridge, the circuit will be closed.

This invention relates generally to pipe coating and has as its primary object the provision of novel apparatus for detecting the presence of holidays in the coating, i.e., portions of the surface of the pipe accidentally left uncovered during the coating operation or chips in the coating resulting from improper handling.

In the preparation of underground and underwater pipes for conveying oil, gas or the like, a protective coating is normally applied to the outer, and sometimes inner, surface of the pipe to prevent or reduce corrosion problems. The pipes are usually constructed of steel which is vulnerable to corrosion, espectially in particular types of soil and water, even if holidays in the coating are very small. Thus, every effort must be made to assure that a complete covering is obtained.

Many attempts have been made to construct apparatus which will effectively detect the presence of holidays but these devices have generally not been capable of efliciently checking the entire coated surface of the pipe. Additionally, the devices heretofore used have often lacked sufficient sensitivity to detect relatively minute holidays.

An important object of the instant invention is to provide apparatus for detecting and marking pipe coating holidays which will be highly effective and capable of loeating the presence of very small discontinuities in the coated surface. More particularly, a liquid bridge is created between proximal portions of the nonconductive coating and a novelly designed electrode disposed in an electrical circuit whereby, when a holiday is contacted by the liquid bridge, the circuit will be completed through the electrically conductive pipe. A marking device is associated with the circuit to properly indicate the particular location of the holiday.

Another object of this invention is to provide a holiday detector utilizing a water bridge as above described wherein a plurality of spaced, yieldable, contoured rollers are provided and disposed in intimate peripheral contact with the coated surface of the pipe. The liquid bridge is formed between the rollers and the pipe to assure complete conductive contact with the surface of the pipe. For optimum results, the rollers are constructed of a fluid-absorbent material, such as cellular sponge, so that the liquid bridge will be effectively maintained through the combined adhesion, cohesion and surface tension characteristics of the liquid with respect to the pipe and rollers.

In the drawing:

FIG. 1 is a fragmentary, side elevational view of an apparatus for detecting and marking pipe coating holidays made pursuant to the teachings of my invention and showing the same in operation;

FIG. 2 is a cross-sectional view taken along line 22 of FIG. 1; and

FIG. 3 is a cross-sectional view taken substantially along line 3-3 of FIG. 1.

The present invention is adapted for use with coated pipes, such as the illustrated cylindrical pipe 10, having a coating 12 On the outer surface thereof. Pipe 10 is positioned for the detecting operation by a pair of supports 14 mounted on a floor surface 15, and each support 14 includes a base 16, a pair of spaced uprights 18- having an axle 2t) rotatably journalled therebetween, and a pair of beveled wheels 22 mounted on axle 20. Pipe 10 rests on beveled wheels 22 and is shifted longitudinally by a suitable means (not shown) in the direction of the arrow in FIG. 1.

The detecting and marking apparatus includes an octagonal frame 24 presenting eight stretches 26 positioned in circumscribing relationship about pipe 10, and frame 24 is supported by a pair of opposed legs 28 which are secured to floor 15. Each stretch 26 is provided with a sleeve 30 rigidly secured thereto, it being noted that sleeves 30 are alternately secured to the opposed faces of frame 24.

A plurality of rollers 32 are spaced in circumscribing relationship about pipe 10 and are each supported by a Z- shaped crank 34 which has an arm 36 thereof journalled in a respective sleeve 30. Each sleeve 30 has a setscrew 38 extending therethrough for engaging arm 36 to prevent relative shifting movement of the latter within sleeve 30. The center arm 40 of each crank 34- extends laterally away from frame 24, and the free arm 42 of crank 34 extends laterally from arm 40 in spaced, overlying relationship with respect to pipe 10.

Each roller 32 is provided with a bore therethrough for rotatably mounting each roller 32 on a respective arm 42. A pair of washers 44 are provided at the opposed ends of each roller 32 and a cotter key 46 is journalled through the outermost end of arm 42 for retaining roller 32 there- 3 on. It will be noted that-the lateral displacement of rollers 32 with respect to frame 24 presents a pair of banks 48 of rollers'32 disposed on opposite sides of frame 24.

Rollers 32 are generally 'cylindrically shaped and are preferably constructed of a yieldable, fluid-absorbent material, such as cellular sponge or other cellular foam material. The outer continuous surface of each roller 32 is contoured to define a concave configuration which complementally engages the arcuate coated surface of pipe 10. Itwill be appreciated that each bank 48 comprises four of the rollers 32, the latter being peripherally spaced at substantially equal 90 intervalsabo-ut pipe 10, each roller 32 engaging approximately 90 of the arcuate surface of pipe 10. As is clear from FIG, 3, the rollers 32 of one bank 48 are longitudinally aligned between respective adjacent rollers of the other bank 48.

A pipe 50 is mounted intermediate its ends on the uppermost stretch 26 of frame 24 and extends laterally therefrom. A water supply line 52 is coupled at one end 54 of pipe 50 and terminates at its lowermost end in a spray ring 56 having a plurality of apertures 58 formed in the inner surfacethereof. A spout 60 is coupled to the other end 62 of pipe 50 and overlies a proximal bank 48 for delivering liquid thereto. A valve 64 is interposed in pipe 50 for controlling the water delivered to spout 60.

A marking device, broadly designated by the numeral 66, is mounted adjacent the coating 12 on pipe and includes a standard 68 secured to floor 15, standard 68 having a bracket 70 extending laterally from the uppermost end thereof in overlying relationship to pipe 10. A solenoid 72 depends from bracket 70 and has a marking pencil 74 disposed adjacent coating 12. Solenoid 72 is connected by a line 76 to a battery 78 which is grounded through line 80. A lead '82 connects solenoid 72 with frame 24 which is suitably insulated with respect to floor and pipe 50.A ground lead 84 is connected to a conductive surface 86 of pipe 10.

In operation, each roller 32 is radially shifted into intimate engagement with proximal portions of coating 12 on the outer surface of pipe 10 by adjustment of crank 34 within sleeve 30. An electrically conductive liquid is directed through pipeline 52 and subsequently to spray ring 56 whereby the liquid will be emitted through apertures 58 onto proximal portions of coating 12. Liquid is also conveyed through pipe 50 and thence through spout 60 to supply liquid to rollers 32. Any number of spouts 60 could be provided as necessary for maintaining sponge rollers 32 in a moistened condition. The combined liquid distribution creates a liquid bridge between rollers 32 and the proximal engaged portions of pipe 10 as the pipe is longitudinally shifted relative to frame 24. The liquid bridge is maintained through the combined adhesion, cohesion and surface tension characteristics of the liquid with respect to coating 12 and fluid-absorbent sponge rollers 32.

The electrical circuit means, which includes the electrical energy battery source 78 and solenoid72 is coupled by lead 82 to moistened rollers 32 which normally engage the nonconductive coating 12. Since the coating 12 prevents completion of an electrical circuit, current will not flow through solenoid 72 for actuating pencil 74 to suitably mark pipe 10. However, if a holiday is engaged by a roller 32 as the latter rotates along the arcuate' coated surface of pipe 10, the liquid bridge will couple the respective roller 32 with a conductive portion of the outer surface of pipe 10 to thereby complete a circuit therethrough to lead 84. Since the circuit is completed, solenoid 72 will be actuated to project pencil 74 downwardly to mark the outer surface of pipe 10 for registering the location of a holiday in pipe 10. Of course, the marking will have a predetermined spaced relationship with respect to, the location of the holiday.

It will be appreciated that the provision of yieldable, contoured rollers 32 assures complete intimate peripheral contact with pipe 10 so that minute holidays may be elficiently detected. The liquid bridge formed between rollers 32 and pipe 10 will immediately and efliciently complete the electrical circuit for registering the presence of a holiday. Also serving to assure that every holiday will be detected, banks 48 have been aligned in staggered relationship so that the spaces between adjacent rollers 32 in one bank 48 will be centrally aligned with the rollers 32 of the other bank. Since each roller 32 engages approximately 90 of the arcuate surface of pipe 10, the overlapping relationship between banks 48 essentially provides a dual detecting apparatus for locating the presence of holidays.

Various sizes of pipe may be accommodated by radially shifting rollers 32 which is accomplished by releasing setscrew 38 and relatively shifting arm 36 within sleeve 30 until the desired position is obtained. The radial shifting of rollers 32 may also be used to compensate for various liquid bridge characteristics and wear of roller 32.

Having thus described the invention, what is claimed as new and desired to be secured by Letters, Patent is:

1. In a coating discontinuity detector,

means adapted for supporting an elongated, electrically conductive object having an outer, generally cylindrical, non-conductive coating thereon;

a scanner assemby including an annular series of iridividually rotatable rollers, each located for longitudinal rolling engagement with the coating of an object supported by said supporting means,

said supporting means and said assembly being adapted to permit relative shifting of the assembly and said object, longitudinally of the latter,

normally interrupted electrical circuit means for indicating coating discontinuities electrically coupled with said rollers and adapted for connection to said object; and

means for distributing an electrically. conductive fluid to said rollers,

said rollers being constructed of resilient, fluid abs0rbent material and each having a peripheral surface contoured for complementally engaging said coating circumferentially thereof, said surfaces being disposed for contacting the entire circumferential extent of said coating whereby upon relative shifting, of the assembly and the object, upon distribution of said fluid to said rollers and upon connection of said circuit means to said object, a circumference encompassing, longitudinally shifting bridge of said liquid is formed between the coating and the rollers for closing said circuit means whenever a discontinuity in the coating is traversed by the bridge regardless of fluctuations in the diameter of said object.

2. The invention of claim 1,

said rollers being disposed in a pair of banks thereof spaced apart longitudinally of said object,

said series of rollers alternating between said banks.

3. The invention of claim 1,

said assembly including a ring shaped frame disposed in circumscribing, radially spaced relationship to said object and means mounting the rollers on the frame radially inwardly thereof,

said mounting means including an irregularly, shaped crank for each roller,

each crank having a radial portion and a second portion extending longitudinally of said object,

said cranks being spaced circumferentially of the frame with the second portions thereof extending alternately in opposite directions,

said rollers being mounted on corresponding second portions at the end of the latter remote from the ra- 1 dial portion presenting a pair of banks of rollers" spaced longitudinally of the object.

4. The invention of claim 1,

and a fluid distributor for wetting said coating with an electrically-conductive fluid ahead of said assembly whereby any discontinuities in said coating are filled with said fluid and the latter assumes the electrical 5 6 potential of the object prior to traversal of the dis- 2,629,002 2/1953 Tinker 324-54 continuity by said bridge. 2,812,491 11/ 1957 Figlio et a1. 324-54 5. The invention of claim 4, 2,900,597 8/ 1959 Goodin-g 324-54 said distributor comprising an annular conduit having 3,045,281 7/1962 Skobel 324-54 X a plurality of radially inwardly directed perforations 5 3,106,677 10/ 1963 Edgar 32465 X therein. 3,267,369 8/ 1966 McLoad 324-54 References Cited I UNITED STATES PATENTS RUDOLPH V. ROLINEC, Primary Examiner. 2,379,947 7/1945 Bandur 324 s4 WALTER CARLSON, Exammer- 2, 71, 60 5/1949 Ev rson et a1. 324-54 G. R. STRECKER, Assistant Examiner. 

1. IN A COATING DISCONTINUITY DETECTOR, MEANS ADAPTED FOR SUPPORTING AN ELONGATED, ELECTRICALLY CONDUCTIVE OBJECT HAVING AN OUTER, GENERALLY CYLINDDRICAL, NON-CONDUCTIVE COATING THEREON; A SCANNER ASSEMBLY INCLUDING AN ANNULAR SERIES OF INDIVIDUALLY ROTATABLE ROLLERS, EACH LOCATED FOR LONGITUDINAL ROLLING ENGAGEMENT WITH THE COATING OF AN OBJECT SUPPORTED BY SAID SUPORTING MEANS, SAID SUPPORTING MEANS AND SAID ASSEMLBY BEING ADAPTED TO PERMIT RELATIVE SHIFTING OF THE ASSEMBLY AND SAID OBJECT, LONGITUDINALLY OF THE LATTER, NORMALLY INTERRUPTED ELECTRICAL CIRCUIT MEANS FOR INDICATING COATING DISCONTINUITIES ELECTRICALLY COUPLED WITH SAID ROLLERS AND ADAPTED FOR CONNECTION TO SAID OBJECT; AND MEANS FOR DISTRIBUTING AN ELECTRICALLY CONDUCTIVE FLUID TO SAID ROLLERS, SAID ROLLERS BEING CONSTRUCTED OF RESILEINT, FLUID ABSORBENT MATERIAL AND EACH HAVING A PERIPHERAL SURFACE CONTOURED FOR COMPLEMENTALLY ENGAGING SAID COATING CIRCUMFERENTIALLY THEREOF, SAID SURFACES BEING DISPOSED FOR CONTACTING THE ENTIRE CIRCUMFERENTIAL EXTENT OF SAID COATING WHEREBY UPON RELATIVE SHIFTING OF THE ASSEMBLY AND THE OBJECT, UPON DISTRIBUTION OF SAID FLUID TO SAID ROLLERS AND UPON CONNECTION OF SAID CIRCUIT MEANS TO SAID OBJECT, A CIRCUMFERENCE ENCOMPASSING, LONGITUDINALLY SHIFTING BRIDGE OF SAID LIQUID IS FORMED BETWEEN THE COATING AND THE ROLLERS FOR CLOSING SAID CIRCUIT MEANS WHENEVER A DISCONTINUITY IN THE COATING IS TRANSVERSED BY THE BRIDGE REGARDLESS OF FLUCTUATIONS IN THE DIAMETER OF SAID OBJECT. 